Protein stabilized antimicrobial composition formed by melt processing

Abstract

A method for forming an antimicrobial composition that includes mixing an antimicrobially active botanical oil (e.g., thymol, carvacrol, etc.) and protein within a melt blending device (e.g., extruder) is provided. Despite the problems normally associated with melt processing proteins, the present inventors have discovered that the processing conditions and components may be selectively controlled to allow for the formation of a stable, melt-processed composition that is able to exhibit good mechanical properties. For example, the extrusion temperature(s) and shear rate employed during melt blending are relatively low to help limit polypeptide dissociation, thereby minimizing the impact of aggregation and embrittlement. While the use of such low temperature/shear conditions often tend to reduce mixing efficiency, the present inventors have discovered that a carrier fluid may be employed to enhance the ability of the botanical oil to flow into the internal structure of the protein where it can be retained in a stable manner. The composition is also typically anhydrous and generally free of solvents. In this manner, the protein will not generally disperse before use and prematurely release the botanical oil.

What is claimed is: 
     
       1. A method for forming a wipe comprising an antimicrobial composition, the method comprising dispersively blending a botanical oil, protein, and carrier fluid within a melt blending device at a temperature of from about 20° C. to about 100° C. and a shear rate of from about 1 to about 100 Pascal-seconds to form the composition, and applying the composition to the wipe, wherein the wipe comprises a fibrous material, wherein botanical oils constitute from about 0.1 wt. % to about 30 wt. % of the composition, proteins constitute from about 30 wt. % to about 95 wt. % of the composition, and carrier fluids constitute from about 1 wt. % to about 50 wt. % of the composition. 
     
     
       2. The method of  claim 1 , wherein the botanical oil includes a monoterpene phenol. 
     
     
       3. The method of  claim 2 , wherein the monoterpene phenol is thymol, carvacrol, or a mixture thereof. 
     
     
       4. The method of  claim 1 , wherein the protein is a plant protein. 
     
     
       5. The method of  claim 4 , wherein the plant protein is wheat gluten. 
     
     
       6. The method of  claim 1 , wherein the carrier fluid is a polyhydric alcohol. 
     
     
       7. The method of  claim 6 , wherein the polyhydric alcohol is glycerol. 
     
     
       8. The method of  claim 1 , wherein the carrier fluid is an aliphatic carboxylic acid. 
     
     
       9. The method of  claim 1 , wherein botanical oils constitute from about 0.5 wt. % to about 20 wt. % of the composition, proteins constitute from about 40 wt. % to about 90 wt. % of the composition, and carrier fluids constitute from about 5 wt. % to about 30 wt. % of the composition. 
     
     
       10. The method of  claim 1 , wherein the composition further comprises a starch polymer. 
     
     
       11. The method of  claim 1 , wherein the botanical oil, protein, and carrier fluid are blended within the melt blending device at a temperature of from about 30° C. to about 80° C. 
     
     
       12. The method of  claim 1 , wherein the botanical oil, protein, and carrier fluid are blended within the melt blending device at a shear rate of from about 5to about 60 Pascal-seconds. 
     
     
       13. The method of  claim 1 , wherein the melt blending device is an extruder. 
     
     
       14. The method of  claim 1 , wherein the fibrous material contains absorbent fibers. 
     
     
       15. The method of  claim 14 , wherein the fibrous material is a composite of absorbent fibers and synthetic thermoplastic fibers. 
     
     
       16. The method of  claim 1 , wherein the composition is in the form of particles. 
     
     
       17. The method of  claim 16 , wherein the particles have an average size of from about 100 micrometers to about 600 micrometers. 
     
     
       18. The method of  claim 1 , wherein the composition is applied to the wipe by printing, dipping, spraying, melt extruding, coating, or foaming. 
     
     
       19. The method of  claim 1 , wherein the composition is applied in a pattern that covers from about 5% to about 95% of a surface of the wipe.